MP3/Transcript
Transcript Text reads: The Mysteries of Life with Tim and Moby A robot, Moby, is selecting music on his portable MP3 player. There are headphones on his head. A boy, Tim, notices what he is doing. TIM: Hey, when did you get that MP3 player? MOBY: Beep. TIM: Aunt Jean? She sent me a pair of socks. Nice socks, but still. MOBY: Beep. Moby gives Tim a smug smile and hands him a sheet of paper. Tim reads from the typed letter. TIM: Dear Moby, Make one of your little movies about MP3 files. The technology is very interesting and useful. From, Aunt Jean. Tim looks toward Moby. TIM: Your movies? MOBY: Beep. Moby smiles. Tim snorts. TIM: Whatever. MP3 is short for MPEG 1 Audio Layer-3. An animation shows sound waves in motion. TIM: MPEG stands for Moving Pictures Expert Group. MOBY: Beep. TIM: Well, that's because the technology was originally developed to compress movies. MP3 is a file format that compresses bytes, the ones and zeros that make up digital information, by a factor of about 10 to one. An animation shows lines of ones and zeros. Text reads: Compression Complete. TIM: The smaller file size means you can fit more sound files in less hard drive space, and downloading and receiving them takes a lot less time. MOBY: Beep. Moby holds up a self-produced CD with his picture on it. Text on the CD case reads: Moby (the robot), My Best Love Songs. TIM: Well, a sound file like the kind you get on a CD is big, around 30 megabytes. It would take a while to download a CD quality song. MP3 compression shrinks the same song down to just a few megabytes, and that's a much more manageable size. MOBY: Beep. TIM: Well, you're losing some information when you compress an audio file from 30 megabytes to three megabytes, but there are some tricks involved. Encoding an MP3 involves a technique called perceptual noise shaping to compress the sound. An animation represents the process Tim describes. TIM: It's based on the fact that our ears don't actually hear every single sound in a song. Our brains process the input from our ears in a very specific way, and as a result, we hear some sounds better than others. An animation represents sound waves reaching a human ear and the brain selectively interpreting the soundwaves. Another animation shows Moby hitting a loud power chord on an electric guitar and fingers snapping. TIM: If two sounds happen at once, we tend to only hear the louder one. The power chord plays at the same time the fingers snap. Sound meters measure the noise, showing that the guitar is louder than the snapping. TIM: And if parts of a sound are pitched too high or too low, we can't hear them at all. An animation compares the high pitch of a ringing bell with the low pitch of a single strike to a bongo drum. In both measurements of the sound waves, some of the waves are outside of what a person can hear. MOBY: Beep. TIM: Yep. There's audio information in songs that the human ear just can't pick up. MP3 compression gets rid of all the stuff that you don't hear anyway. MOBY: Beep. TIM: You don't necessarily need a portable MP3 player to play MP3 files. A computer equipped with a sound card, speakers, and an MP3-playing program can play MP3 files. Tim pats the top of a computer. TIM: And with special software you can encode your own CDs onto MP3s. Moby inserts his CD into the computer. MOBY: Beep. TIM: Right. That's called ripping. So, um, can I borrow your MP3 player? MOBY: Beep. TIM: Aw, please? I'm getting tired of carrying this enormous boom box around. Tim lifts an abnormally large boom box. A rim-shot sounds and Tim looks at the MP3 player. TIM: Wow, that thing is loud. Category:BrainPOP Transcripts